Enjoy Man Utd experience: Colosimo

Veteran defender Simon Colosimo has a simple message to those A-League players with the once-in a-lifetime opportunity to take on Manchester United in Australia: enjoy yourselves.

Colosimo was part of the Socceroos team that clashed with the English Premier League side on their most recent visit to Australia, in 1999.

The then 20-year-old was crunched by an Andy Cole tackle at Sydney's ANZ Stadium that left him needing a knee reconstruction.

Rather than harbouring any resentment or bitterness toward the Red Devils, the 34-year-old looks back on the occasion with fondness and reverence.

"I was only young and I was in awe of most of the players ... I think everyone who plays against Manchester United, there's going to be that little bit of intimidation because of their profile," Colosimo told AAP.

"It (the A-League Allstars clash with United on July 20) is an occasion where you have to enjoy every moment as a player, because the game's only 90 minutes and before you know it the game's done.

"Get ready to enjoy yourselves (would be my advice to the Allstars). It's not often that a big club comes to Australia, let alone Manchester United."

Professional Footballers Australia president Colosimo wrapped up negotiations with Football Federation Australia (FFA) for the A-League's new collective bargaining agreement this week.

Putting on his PFA hat, Colosimo said the upcoming United match proved how far soccer had come in 14 years.

"We're able to have an Allstars team against Manchester United. When we were there (in 1999), it was as the Socceroos," he said.

"It says a lot about the A-League and the game in this country, and hopefully in time it's Man United against one of the A-League clubs."

Colosimo, who plied his trade with Perth Glory, Sydney FC and most recently captained Melbourne Heart, is now preparing for a stint with Indian I-League club Dempo.

Fans have cast their vote for the Allstars team and coach Ange Postecoglou will name his final squad on July 13 ahead of a week-long training camp in Sydney.

The availability of Italian superstar Alessandro Del Piero, who topped the voting for strikers, is yet to be confirmed by FFA.